NEW YORK (Reuters Health) – From 1985 to 2007, the initial CD4+ cell counts seen at diagnosis in HIV-infected patients in the US have fallen, suggesting that the virus may be adapting to the host and becoming more virulent, according to a report in the May issue of Clinical Infectious Diseases.

“Our observations agree with those of other investigators, who have observed that patients starting HIV care more recently may be presenting with lower initial CD4+ cell counts and requiring antiretroviral therapy initiation earlier in the disease course,” Dr. Nancy Crum-Cianflone, from the Naval Medical Center, San Diego, California, and colleagues state.

The findings stem from an analysis of data for 2174 HIV seroconverters who were enrolled in the TriService AIDS Clinical Consortium HIV Natural History Study. The subjects were all antiretroviral-naive and had a CD4+ count measured within 6 months of their HIV diagnosis.

The average initial CD4+ cell counts during the periods 1985-1990, 1991-1995, 1996-2001, and 2002-2007 were 632, 553, 493, and 514 cells/microliter, respectively. During the same periods, the percentages of subjects with initial CD4+ cell counts below 350 cells/microliter were 12%, 21%, 26%, and 25%.

The reduction in initial CD4+ cell counts was similar in African American and white patients, the report indicates. Similar trends were also noted with the CD4+ cell count percentage and the total lymphocyte count.

In an accompanying editorial, Dr. Maria Dorrucci, from Istituto Superiore di Sanita, Rome, and Dr. Andrew Phillips, from University College Medical School, London, comment that while some studies, such as the current one, have suggested that HIV virulence is increasing, others have found that it is either stable or decreasing.

This, they note, may relate to how virulence is assessed, adding that “it is unclear whether simple immunological or virological proxies for virulence can be expected to adequately capture the whole complexity of HIV virulence and host susceptibility.”

Reference:
Clin Infect Dis 2009;48:1285-1295.